System and Method for Virtual Multi-Point Transceivers

ABSTRACT

A method embodiment includes receiving, by a network device, a cooperation candidate set (CCS) and determining a cooperation active set (CAS). The CCS includes a plurality of potential cooperating user equipment (CUEs) for selection to the CAS, and the plurality of potential CUEs is selected from a plurality of user equipment (UEs) in the network. The CAS is a set of CUEs selected from the CCS. A target user equipment (TUE) and the set of CUEs form a virtual multipoint transceiver.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/256,238, filed on Sep. 2, 2016 and entitled “System and Method forVirtual Multi-Point Transceivers,” which is a continuation of U.S.patent application Ser. No. 14/177,019, now U.S. Pat. No. 9,439,176,filed on Feb. 10, 2014 and entitled “System and Method for VirtualMulti-Point Transceivers,” which applications are hereby incorporatedherein by reference.

TECHNICAL FIELD

The present invention relates generally to a system and method forwireless communications, and, in particular embodiments, to a system andmethod for device-centric transmitter and receiver virtualization.

BACKGROUND

Generally, future wireless networks may be more interference dominant,with ultra-dense deployment of transmission points. One method ofmanaging interference and improving received signal quality involvesoperating the network in a hyper transceiver mode. Operating in a hypertransceiver mode relies on group-2-group (G2G) communications between aset of cooperative transmitters and a set of cooperative receivers. Forexample, a user equipment (UE) in a network may form a cooperativedevice mesh with other UEs to communicate cooperatively with one or moretransmitters. These cooperative device meshes may be referred to asvirtual multipoint transceivers and may be dynamically configured basedon network conditions such as resource availability, UE cooperationstrategies, channel conditions, and the like. Each virtual multipointtransceiver may include a target UE and a set of cooperating UEs, whichhelp the target UE in uplink/downlink transmissions.

Furthermore, a transmission point in the network may form a cooperativecloud radio access network (CRAN) cluster with other transmission pointsto communicate cooperatively with the one or more virtual multipointtransceivers. These cooperative CRAN clusters may be referred to asvirtual transmitters and may be dynamically configured based on networkconditions such as resource availability, virtual multipoint transceivercooperation strategies, channel conditions, energy savingconsiderations, and the like. Each virtual transmitter may include oneor more serving transmission points, which can be dynamically updated inorder to provide tailored quality of service/experience (QoS/QoE) tovirtual multipoint transceivers. Dynamic point selection (DPS) is onesuch transmitter virtualization technique that dynamically tailors theserving transmission point to a specific target UE.

However, as the number of cooperating UEs and/or transmission pointsincreases, the complexity of managing the virtualtransmitters/transceivers (e.g., encoding/decoding complexities) alsoincreases. Thus, while numerous cooperating transmission points and UEsmay be selected for improved signal quality of a target UE, complexityconsiderations and/or energy saving aspects may limit the total numberof cooperating transmission points and UEs used during transmission.Furthermore, the ability to dynamically reconfigure virtualtransmitters/transceivers based on network conditions may also belimited by a desire to maintain the selection process at manageablecomplexity.

SUMMARY

These and other problems are generally solved or circumvented, andtechnical advantages are generally achieved, by preferred embodiments ofthe present invention which provides a system and method fordevice-centric transmitter and receiver virtualization.

In accordance with an embodiment, a method for forming a virtualmultipoint transceiver includes a cooperation candidate set (CCS) anddetermining a cooperation active set (CAS). The CCS includes a pluralityof potential cooperating user equipment (CUEs) for selection to the CAS,and the plurality of potential CUEs is selected from a plurality of userequipment (UEs) in the network. The CAS is a set of CUEs selected fromthe CCS. A target user equipment (TUE) and the set of CUEs form avirtual multipoint transceiver.

In accordance with another embodiment, a network device includes aprocessor, a computer readable storage medium storing programming forexecution by the processor, and a transmitter for signaling a selectedoperation mode to a radio node in a network. The programming includesinstructions to determine a cooperation candidate set (CCS) anddetermine a cooperation active set (CAS). The CCS includes a pluralityof potential cooperating user equipment (CUEs) for selection to the CAS,and the plurality of potential CUEs is selected from a plurality of userequipment (UEs) in the network. The CAS is a set of CUEs selected fromthe CCS. A target user equipment (TUE) and the set of CUEs form thevirtual multipoint transceiver.

In accordance with yet another embodiment, a method for forming avirtual multipoint transceiver includes determining, by a networkdevice, a cooperating candidate set (CCS) and determining a CAS from theCCS. The CCS includes a plurality of potential cooperating userequipment (CUEs), and the CAS is a set of CUEs selected from the CCS. Atarget user equipment (TUE) and the set of CUEs form a virtualmultipoint transceiver.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention, and theadvantages thereof, reference is now made to the following descriptionstaken in conjunction with the accompanying drawing, in which:

FIGS. 1A and 1B are block diagrams of a network having virtualmultipoint transceivers in accordance with various embodiments;

FIG. 2 illustrates a flow diagram of a method for selecting cooperatinguser equipment (CUE) for a virtual multipoint transceiver in accordancewith various embodiments;

FIGS. 3 and 4 illustrate flow diagrams of a method for selecting CUEsfor a virtual multipoint transceiver in accordance with variousalternative embodiments;

FIGS. 5A and 5B illustrate flow diagrams of methods for determiningcooperating candidate sets (CCS) and cooperating active sets (CAS) inaccordance with various embodiments; and

FIG. 6 is a block diagram of a computing system, which may be used toimplement various embodiments.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The making and using of embodiments are discussed in detail below. Itshould be appreciated, however, that the present invention provides manyapplicable inventive concepts that can be embodied in a wide variety ofspecific contexts. The specific embodiments discussed are merelyillustrative of specific ways to make and use the invention, and do notlimit the scope of the invention.

Various embodiments are described in a specific context, namely adynamic point selection (DPS) based network architecture usinggroup-2-group (G2G) communications between a user equipment (UE) centrictransmission point cluster (e.g., a virtual transmitter) and a UEcentric virtual multipoint transceiver. Other embodiments, however, maybe directed to any other network architectures having UE centric virtualtransmitters and/or receivers, such as, a multicasting/multipath networkarchitecture with collaborative network/rateless/fountain coding,cooperative multipoint (CoMP) based networks, or the like.

Various embodiments involve the selection of UE centric virtualmultipoint transceivers. Devices (e.g., UEs) of the virtual multipointtransceiver acts as a virtual transmitter during uplink and/or a virtualreceiver during downlink. Each virtual multipoint transceiver includesone or more target UE (TUEs) and a plurality of cooperating UEs (CUEs).The CUEs help the TUE communicate with the network, for example, duringdownlink reception and/or uplink transmission of data packets. Thus, theuse of virtual multipoint transceivers improves overall throughput andcoverage in the network. Selection of CUEs may include first selecting aTUE-centric cooperation candidate set (CCS) of potential CUEs, forexample, based on relatively simplistic selection criteria (e.g.,received reply content/signal strength or UE location). Then, acooperation active set (CAS) is selected from the CCS. The CAS is theCUEs that, together with the TUE, form the virtual multipointtransceiver. The CAS may be selected from the CUE based on access linkand/or device-2-device (D2D) link qualities. Rather than consider allthe UEs in a network (or all UEs within transmission range of a TUE) forCAS selection, the pre-selection of a CCS decreases the number of UEsfor CAS selection to a manageable level. Thus, a UE-centric lowcomplexity design for selecting cooperating UEs in a virtual multipointtransceiver while accounting for access link/D2D link quality isprovided. Furthermore, the CCS and CAS may be configured based onlong-term quality measurements to avoid the complexity of dynamic,real-time link assessment/selection.

FIG. 1A illustrates a block diagram of a network 100, which may operatein a dynamic point selection (DPS) system architecture in accordancewith various embodiments. Network 100 includes a plurality of radionodes, such as transmission points 102 and UEs 104. Transmission points102 may be, for example, base stations, long term evolution (LTE)eNodeBs, WiFi access points, and the like. Alternatively, transmissionpoints 102 may be virtual transmission points. For example, transmissionpoints 102 may be a cluster of one or more traditional transmissionpoints (e.g., base stations/eNodeBs/etc.) jointly communicating with UEs104. Each virtual transmission point 102 may be selected based onquality of service (QoS) requirements, neighborhood relationships, andthe like of a UE (e.g., TUE 104 a).

Communications in network 100 may be between transmission points 102 anda device-centric virtual multipoint transceiver 106. Virtual multipointtransceiver 106 allows a TUE 104 a to cooperatively receivedownlink/transmit uplink packets with CUEs 104 b. UEs 104 may beoperating in an active state (e.g., actively receiving data from thenetwork) or in an idle state (e.g., not actively receiving data from thenetwork). Furthermore, some CUEs 104 b may be dummy UEs, which may bestrategically deployed UEs for helping TUE 104 a.

Virtual multipoint transceiver 106 may be assigned a group ID by thenetwork (e.g., by a network controller) for joint reception oftransmissions. For example, in downlink transmissions a transmissionpoint 102 associated with a particular virtual multipoint transceivermay multicast a transmission for TUE 104 a to all the UEs in virtualmultipoint transceiver 106 as identified by its network-assigned groupID. Packets from transmission point 102 to TUE 104 a may be sent in twotransmission phases. In the first transmission phase (known as thedownlink multicast phase), transmission point 102 may multicast atransmission to virtual multipoint transceiver 106 (i.e., TUE 104 a andCUEs 104 b) across access links 112. In the second transmission phase(known as the data forwarding phase), CUEs 104 b may forward receivedportions of the multicast transmission to TUE 104 a across D2D links114. In some embodiments, CUEs 104 b may relay received portions of themulticast transmission using a decode-and-forward (DF) relay protocol.For example, CUEs 104 b may decode the whole codeword of the receivedmulticast transmission, re-encode the codeword, and forward there-encoded transmission (or a portion thereof) to the TUE 104 a acrossD2D links 114. Upon reception, TUE 104 a may combine informationreceived during the downlink multicast phase and the data forwardingphase to decode the transmission sent by the network. A similarprocedure may be applied for uplink transmissions. Furthermore, CUEs 104b may operate in a half-duplex mode or a full-duplex mode. In ahalf-duplex mode, CUEs 104 b may not receive data from the network andsimultaneously forward data to TUE 104 a in the same time and frequencyresources. In a full-duplex mode, CUEs 104 b may receive data andforward data simultaneously. Other forwarding protocols, such asamplify-and-forward (where CUEs 104 b transmit an amplified version ofthe received multicast transmission to TUE 104 a), compress-and-forward(where CUEs 104 b quantizes the received multicast transmission andtransmits a re-encoded quantized multicast transmission to TUE 104 a),or the like, may also be used.

CUEs 104 b may be selected on a TUE 104 a centric basis. For example, aCCS 110 of potential CUEs 104 c may be selected for a TUE based onrelatively simple selection criteria (e.g., received replycontent/signal strength or UE location). Then a CAS 108 may be selectedfrom the potential CUEs 104 c of CCS 110 based on quality of accesslinks 112 (e.g., between the potential CUEs 104 c and a transmissionpoint 102) and/or D2D links 114 (e.g., between the potential CUEs 104 cand TUE 104 a). CAS 108 includes CUEs 104 b, which together with TUE 104a form virtual multipoint transceiver 106. The selection criteria forCCS 110 and CAS 108 may be described in greater detail in subsequentparagraphs.

Because the selection of CUEs 104 b is TUE 104 a centric, configurationsof virtual multipoint transceivers 106 may vary across network 100 basedon which UEs are TUEs 104 a. Furthermore, although a particularconfiguration of network 100 is illustrated in FIG. 1A, other networksmay include different configurations of and a number of network elements(e.g., transmission points 102/UEs 104). Based on changes in networkconditions (e.g., quality of access links 112/D2D links 114), CCS 110and CAS 108 may be updated semi-statically. For example, CCS 110 may beupdated every several hundred transmission time intervals (TTIs), andCAS 108 may be updated every hundred TTIs. Less frequent updates maysimplify the complexity of measuring or predicting access links 112/D2Dlinks 114. Other time intervals for updating CCS 110 and CAS 108 may beapplied in alternative embodiments.

In other embodiments, updating CCS 110 and/or CAS 108 may also be basedon the changes to the transmission points 102 associated with TUE 104 a,CUEs 104 b, and/or potential CUEs 104 c. For example, a virtualtransmission point 102 may be dynamically selected for a virtualmultipoint transceiver 106 based on the status (e.g., QoE requirements,neighborhood relations, and the like) of TUE 104 and/or network status(e.g., energy saving considerations). Based on TUE 104 status and/ornetwork status, the virtual transmission point 102 may be dynamicallyupdated, and based on this dynamic updating, the virtual multipointtransceiver 106 may also be updated.

Furthermore, although virtual multipoint transceiver 106 is illustratedas having one TUE 104, in other embodiments, a virtual multipointtransceiver 106 may include multiple TUEs 104. For example, duringmulticast transmission, transmission points 102 may send the same packetto more than one UE. Thus, a virtual multipoint transceiver 106 may beformed having more than one TUE 104. In such embodiments, the selectionof the virtual multipoint transceiver 106 may be based on D2D linkquality, access link quality, location, capacity, and/or other selectioncriteria of all TUEs 104.

FIG. 1B illustrates a block diagram of network 120 operating in amulticasting/multipath system architecture in accordance with variousalternative embodiments. Network 120 may be substantially similar tonetwork 100, wherein like reference numerals represent like elements.For example, network 120 may include UEs 104. Communications between TUE104 a and the network may be done through a virtual multipointtransceiver 106, which may include CUEs 104 b helping TUE 104 a inuplink transmissions/downlink reception. Virtual multipoint transceiver106 may be formed by selecting a CCS 110 and a CAS 108 on a TUE 104 acentric basis.

However, transmission points 102 in network 120 may not be dynamicallyselected on a TUE 104 a centric basis. Instead, individual transmissionpoints 102 may cooperatively transmit packets to TUE 104 a, for example,using a collaborative, rateless network-coding scheme. Other cooperativetransmission schemes may also be used. Furthermore, CUEs 104 b and/orpotential CUEs 104 c may be associated with the same or differenttransmission points 102 as TUE 104 a. For example, compared to network100, network 120 may not use G2G communications (e.g., network 120 maynot include a virtual transmission point communicating with a virtualreception point). Instead, UEs 104 may be associated with one or moretransmission points 102, which may be the same or different transmissionpoints 102 associated with CUEs 104 b/potential CUEs 104 c.

FIG. 2 illustrates a flow chart of a method 200 of selecting a virtualmultipoint transceiver using a TUE selected CCS and a network controlledCAS in accordance with various embodiments. In step 202, a TUE (e.g.,TUE 104 a) seeks to form a virtual multipoint transceiver, for example,by broadcasting a cooperation seeking request (CSR) message toneighboring UEs (e.g., UEs 104 within transmission range of TUE 104 a).The decision to form a virtual multipoint transceiver may be triggeredby the TUE itself or by a network controller. For example, the networkcontroller may instruct the TUE to from a virtual multipoint transceiverbased on channel quality measurements (e.g., a channel quality indicator(CQI) report) of the TUE, retransmission times, retransmissionfrequency, or the like. The TUE may multicast the CSR message over D2Dlinks (e.g., D2D links 114). In step 204, the TUE receives replies fromUEs capable of and willing to form a virtual multipoint transceiver withthe TUE. Next, in step 206, the TUE compiles a set of potential CUEs andgenerates a CCS. The potential CUEs may be selected from a plurality ofUEs in the network, for example, based on relatively simple selectioncriteria such as the content and/or strength of received replies to theCSR message, physical proximity to the TUE, network associations (e.g.,being connected to a same network or a different network), or the like.Steps 204 through 206 may be referred to as a potential CUE discoveryphase. In step 208, the TUE informs the network (e.g., a transmissionpoint 102 serving the TUE) about the selected CCS. CCSs in a network maybe TUE-specific. Therefore, different TUEs in the network may selectdifferent CCSs.

In step 210, the network (e.g., transmission point 102) selects a CASfrom the CCS for the TUE. In various embodiments, the CAS may beselected based on predicted availability of a potential CUE (e.g., basedon UE traffic load), access link quality between a potential CUE and thetransmission point (e.g., based on MIMO decoding capability), the numberof reception antennas, mobility, a CQI report, D2D quality between thepotential CUE and the TUE, combinations thereof, and the like. In step212, the network informs the TUE of the selected CAS. The CAS is the setof CUEs, which together with the TUE form a virtual multipointtransceiver. The network may select a different CAS from correspondingCCSs for each TUE in the network. In step 214, the network may begincommunicating with the TUE using the selected CAS to operate as avirtual multipoint transceiver.

FIG. 3 illustrates a flow chart 300 of a method of selecting a virtualmultipoint transceiver using a network controlled CCS and a TUE selectedCAS in accordance with various embodiments. In step 302, the networkdetermines a virtual multipoint transceiver may be formed for a TUE. Thenetwork may determine a virtual multipoint transceiver may be formedbased on receiving a CSR message from a TUE (e.g., the TUE may transmitthe CSR message to a transmission point 102 serving the TUE). In otherembodiments, the network may decide to form a virtual multipointtransceiver based channel quality measurements (e.g., a CQI report) ofthe TUE, retransmission times, retransmission frequency, or the like. Instep 304, the network may compile a set of potential CUEs and generate aCCS for the TUE. The potential CUEs may be selected from a plurality ofUEs in the network (e.g., all available UEs in the network) based onrelatively simplistic selection criteria using status information of thepotential CUEs and/or the network (e.g., location information, pathlossinformation, shadowing information, energy saving considerations, andthe like). For example, the potential CUEs may be UEs within a certaindiameter (e.g., with loom) of the TUE. As another example, the networkmay consider energy saving considerations and turn-off (or deactivate)certain transmission points 102. Thus, potential CUEs served by theseinactive transmission points may not be selected for the CCS. In step306, the network informs the TUE of the chosen CCS.

In step 308, the TUE may transmit a CSR message to potential CUEs in theCCS provided by the network. In step 310, the TUE may select a CAS fromthe potential CUEs of the CCS for forming a virtual multipointtransceiver. The selection of the CAS may be in accordance with receivedsignal quality and/or content of replies to the CSR request. Because thereplies may be sent over the D2D link, the CAS may be selected based onpredicted D2D link quality. In such embodiments, the TUE may receiveaccess link quality assessments from the potential CUEs in the reply,and the CAS selection may also account for access link quality ascommunicated. Next, in step 312, the TUE may inform the network of itsselected CAS. Finally, in step 314, the network may begin communicatingwith the TUE using the selected CAS to operate as a virtual multipointtransceiver.

FIG. 4 illustrates a flow chart 400 of a method of a network/TUE jointlyselected CAS in accordance with various embodiments. In step 402, a CCSis compiled. For example, the CCS may include potential CUEs selectedeither by the network or the TUE as described in FIG. 2 or 3, above. Instep 404, the TUE may rank the potential CUEs in the CCS according to anestimate of long-term end-to-end average capacity of the CUE withrespect to all transmission points 102 in each potential CUE's servingset. A potential CUE's serving set may include all transmission points102 that could potentially form an access link with the potential CUE.Alternatively, the serving set may be any subset of transmission pointsof a virtual transmitter or any transmission point in a cloud radioaccess network (CRAN) cluster. The long term end-to-end average capacitymay be calculated by the TUE using any suitable method. For example, forUEs operating in a half-duplex mode, the capacity of each potential CUEwith respect to a particular transmission point may be estimated basedend-to-end average capacity metrics in accordance with the half-duplexmode. An example formula for estimating the capacity using capacitymetrics for a half-duplex mode is:

$C_{{TP}_{i}->{{CUE}_{j}->{TUE}}}^{{HD},{CUE}_{j}} = {\frac{1}{2}{\log_{2}\left( {1 + {\min \left\{ {{SINR}_{{TPi}->{CUEj}},{SINR}_{{CUEj}->{TUE}}} \right\}}} \right)}}$

C_(TPi->CUEj->TUE) ^(FD,CUEj) is the estimated long term end-to-endaverage capacity of a potential CUE_(j) with respect to a transmissionpoint TP_(i). That is, C_(TPi->CUEj->TUE) ^(FD,CUEj) is an estimate ofcapacity for transmitting from TP_(i) through CUE_(j) to the TUE.SINR_(TPi->CUEj) is the signal to noise ratio (SINR) between CUE_(j) andTP_(i) (i.e., access link quality), and SINR_(CUEj->TUE) is the SINRbetween CUEj and the TUE (i.e., D2D link quality). SINRs of access linksmay be estimated based on long-term performance measurements signaled bythe transmission points to the TUE. SINRs of D2D links may be estimated,for example, based on received replies to a CSR message, or the like. Asanother example, for UEs operating in a full-duplex mode, the capacityof each potential CUE with respect to a particular transmission pointmay be estimated based on end-to-end capacity metrics in accordance withthe full-duplex mode. An example formula for estimating the capacityusing capacity metrics for a full duplex mode is:

$C_{{TPi}->{{CUEj}->{TUE}}}^{{FD},\; {CUEj}} = {\log_{2}\left( {1 + {\min \left\{ {\frac{{SINR}_{{TPi}->{CUEj}}}{1 + {SINR}_{CUEj}^{RLI}},{SINR}_{{CUEj}->{TUE}}} \right\}}} \right)}$

SINR_(CUEj) ^(RLI) is a residual loop interference of CUEj in the fullduplex mode. The residual loop interference for full duplex relays maybe estimated using any suitable estimation process.

In step 406, the TUE informs the network with the ranked list ofpotential CUEs. In step 408, the network may select the best K potentialCUEs as the CAS. K is a configurable size of the CAS, for example, basedon the desired level of complexity of virtual multipoint transceivers inthe network. The selected CUEs may change depend on which transmissionpoints 102 are currently associated with potential CUEs in the CCS.

In the embodiments described above, the CCS may be selected based onrelatively simplistic selection criteria, such as, location of UEsrelative to the TUE, received signal strength/content of a reply signal,or the like. Subsequently a CAS may be selected from the CCS based onestimated capacity, access link quality, D2D link quality, or acombination thereof. The pre-selection of the CCS based on relativelysimplistic criteria reduces the estimation and link quality measurementsnecessary for selecting the CAS and thereby reduces the complexity ofvirtual multipoint transceiver configuration to a manageable level. Forexample, rather than predicting capacity/link quality for hundreds ofUEs in a network, the CCS may include about ten potential CUEs. Thenumber of CUEs in the CAS may also be selected to maintain transmissioncomplexity (e.g., decoding complexity) at a manageable level. Forexample, the number CUEs in the CAS may be about two or three. Ofcourse, depending on available resources of the network/TUE, a greateror fewer number of UEs may be selected for the CCS and/or the CAS.Furthermore, the CCS and the CAS may be updated on a semi-static basisto reduce the number of measurements taken in a network. That is, theCCS and the CAS may be based on long term performance measurements. Forexample, the CAS may be selected every hundred TTIs, and the CCS may beupdated every few hundred TTIs.

FIGS. 5A and 5B are flow charts of methods for determining a CCS and aCAS in accordance with various embodiments. FIG. 5A is directed towardscompiling a CCS whereas FIG. 5B is directed towards selecting a CAS fromthe CCS. Referring to FIG. 5A, in step 502, a network device compiles aCCS for a specific TUE. The CCS is a set of potential CUEs selected froma plurality of UEs in the network (e.g., the CCS is a subset of allavailable UEs in the network) for forming a virtual multipointtransceiver with the TUE. The CCS may be TUE-centric (e.g., differentCCSs may be compiled for different TUEs in the network). The networkdevice may be the TUE or a transmission point. For example, inembodiments where the network device is a TUE, the TUE may transmit aCSR message to other UEs in the network, receive replies to the CSRmessage, and compile a CCS based on the replies (e.g., based on signalstrength and/or content of the replies). In other embodiments where thenetwork device is a transmission point, the CCS may be compiled based onlocation information of potential CUEs, shadowing information ofpotential CUEs, pathloss information of potential CUEs, energy savingconsiderations, and/or the like in relation to the TUE in the network.In such embodiments, the network device may be triggered to compile theCCS based on a CSR message from the TUE.

Next in step 504, the network device determines the CAS. The CAS is aset of CUEs selected from the CCS, wherein the set of CUEs and the TUEform a virtual multipoint transceiver. Determining the CAS may includetransmitting the CCS to another network device and receiving the CASfrom the other network device (e.g., the TUE or a transmission point).In such embodiments, the other network device selects the CAS from theCCS. Alternatively, determining the CAS may be a joint operation betweenthe two network devices.

Referring next to FIG. 5B, in step 510, the network device determinesthe CCS. For example, the network device may receive the CCS fromanother network device. Alternatively, the network device may compilethe CCS. In step 514, the network device may determine the CAS from theCCS. Determining the CAS may include the network device selecting theCAS from the CCS. For example, when the network device is a transmissionpoint, the CAS may be selected from the CCS based on estimatedavailability of potential CUEs, access link quality between thepotential CUEs and the transmission point (e.g., based on MIMO decodingcapability, the number of reception antennas, mobility, a channelquality indicator (CQI) report), D2D quality between the potential CUEand the TUE, and/or the like. In other embodiments where the networkdevice is the TUE, selecting the CAS may include transmitting a CSRmessage to potential CUEs in the CCS and selecting the CAS based onreplies to the CSR message (e.g., based on content and/or signalstrength of the replies).

In other embodiments, determining the CAS may include helping anothernetwork device to jointly select the CAS. For example, the networkdevice may rank the potential CUEs in the CCS based on estimatedlong-term end-to-end capacity (e.g., for a full-duplex mode or ahalf-duplex mode). The ranked list may be transmitted to another networkdevice, which may select the CUEs based on the ranked list and(optionally) other network information known to the other network device(e.g., current associations between transmission points and potentialCUEs). The selected CAS may then be transmitted to the network device.

FIG. 6 is a block diagram 600 of a processing system that may be usedfor implementing the devices and methods disclosed herein. Specificdevices may utilize all of the components shown, or only a subset of thecomponents, and levels of integration may vary from device to device.Furthermore, a device may contain multiple instances of a component,such as multiple processing units, processors, memories, transmitters,receivers, etc. The processing system may comprise a processing unitequipped with one or more input/output devices, such as a speaker,microphone, mouse, touchscreen, keypad, keyboard, printer, display, andthe like. The processing unit may include a central processing unit(CPU), memory, a mass storage device, a video adapter, and an I/Ointerface connected to a bus.

The bus may be one or more of any type of several bus architecturesincluding a memory bus or memory controller, a peripheral bus, videobus, or the like. The CPU may comprise any type of electronic dataprocessor. The memory may comprise any type of system memory such asstatic random access memory (SRAM), dynamic random access memory (DRAM),synchronous DRAM (SDRAM), read-only memory (ROM), a combination thereof,or the like. In an embodiment, the memory may include ROM for use atboot-up, and DRAM for program and data storage for use while executingprograms.

The mass storage device may comprise any type of storage deviceconfigured to store data, programs, and other information and to makethe data, programs, and other information accessible via the bus. Themass storage device may comprise, for example, one or more of a solidstate drive, hard disk drive, a magnetic disk drive, an optical diskdrive, or the like.

The video adapter and the I/O interface provide interfaces to coupleexternal input and output devices to the processing unit. Asillustrated, examples of input and output devices include the displaycoupled to the video adapter and the mouse/keyboard/printer coupled tothe I/O interface. Other devices may be coupled to the processing unit,and additional or fewer interface cards may be utilized. For example, aserial interface card (not shown) may be used to provide a serialinterface for a printer.

The processing unit also includes one or more network interfaces, whichmay comprise wired links, such as an Ethernet cable or the like, and/orwireless links to access nodes or different networks. The networkinterface allows the processing unit to communicate with remote unitsvia the networks. For example, the network interface may providewireless communication via one or more transmitters/transmit antennasand one or more receivers/receive antennas. In an embodiment, theprocessing unit is coupled to a local-area network or a wide-areanetwork for data processing and communications with remote devices, suchas other processing units, the Internet, remote storage facilities, orthe like.

While this invention has been described with reference to illustrativeembodiments, this description is not intended to be construed in alimiting sense. Various modifications and combinations of theillustrative embodiments, as well as other embodiments of the invention,will be apparent to persons skilled in the art upon reference to thedescription. It is therefore intended that the appended claims encompassany such modifications or embodiments.

What is claimed is:
 1. A method for forming a virtual multipointtransceiver comprising: receiving, by a network, a cooperation candidateset (CCS) for a target user equipment (TUE), wherein the CCS comprises aplurality of potential cooperating user equipment (CUEs) for selectionto a cooperation active set (CAS); and transmitting, by the network, theCAS selected from the CUEs of the CCS, wherein a target user equipment(TUE) and a set of CUEs in the CAS form the virtual multipointtransceiver.